A sterndrive, which is one type of an inboard-outboard drive, is a main device comprising an engine and an outdrive unit. The engine is mounted inside the hull, and transmits driving power to the outdrive unit, which is mounted outside the hull. Recently, sterndrive units that allow trolling have also been developed as per user demands. Among such sterndrive units are, for example, those disclosed in Patent Literatures 1 and 2.
In the sterndrive unit disclosed in Patent Literature 1, a hydraulic clutch and a hydraulic circuit for operating the hydraulic clutch are located inboard. The hydraulic circuit also includes a switching valve for switching between forward and reverse propulsion, and a pressure-reducing valve for trolling. However, the hydraulic clutch and hydraulic circuit located inboard reduce the space available inside the boat. For this reason, Patent Literature 2 discloses locating a hydraulic clutch for trolling in an outdrive unit mounted outboard.    [PTL 1] Japanese Unexamined Patent Publication No. 1999-182582    [PTL 2] Japanese Examined Utility Model Publication No. 1984-4879
Because there is not a large amount of space that can be used inside an outdrive unit, it is necessary to save space in the positioning of a hydraulic circuit. Easy maintenance is also desired for an outdrive unit. However, in the device of Patent Literature 2, although the hydraulic clutch is located outboard, there is no specific disclosure of a hydraulic circuit for trolling control.
The present invention has been made in order to solve the above-described problem. An object of the invention is to provide an outdrive unit that allows space to be saved in the positioning of a hydraulic circuit for trolling, and that enables easy maintenance of the hydraulic circuit for trolling.